Azathioprine therapy for steroid-resistant Henoch-Schönlein purpura: a report of 6 cases.

BACKGROUND: A small percentage of children with Henoch-Schönlein purpura (HSP) develop a chronic form of the disease that often requires prolonged corticosteroid therapy. Disease modifying anti-rheumatic agents (DMARDs) or biologics have been successfully used to treat those refractory cases. Azathioprine is a DMARD that has been reported to be effective in HSP nephritis and in adult cutaneous leukocytoclastic vasculitis, a condition with cutaneous histology similar to HSP. CASE PRESENTATION: A description of 6 cases with relapsing HSP without significant renal involvement, treated with azathioprine are reported. All 6 cases met the classification criteria for the diagnosis of HSP, had relapsing symptoms despite corticosteroid use, were successfully treated with azathioprine and were tapered off of corticosteroids. The duration of azathioprine therapy ranged from 7-21 months and no adverse events were reported. CONCLUSIONS: Azathioprine is effective in controlling prolonged relapsing symptoms of HSP, allowing earlier discontinuation of corticosteroids. This report shows that azathioprine can be included in the therapeutic options for relapsing HSP and is the first case series in the literature of azathioprine use in HSP without significant renal involvement.

Influence of biologically inspired nanometer surface roughness on antigen-antibody interactions for immunoassay-biosensor applications.

Current research efforts to improve immunoassay-biosensor functionality have centered on detection through the optimal design of microfluidic chambers, electrical circuitry, optical sensing elements, and so on. To date, little attention has been paid to the immunoassay-biosensor membrane surface on which interactions between antibodies and antigens must occur. For this reason, the objective of the present study was to manipulate the nanometer surface roughness of a model immunoassay-biosensor membrane to determine its role on sensitivity and specificity. It was hypothesized that surface roughness characteristics similar to those used by the body's own immune system with B-lymphocyte cell membranes would promote antigen-antibody interactions and minimize non-specific binding. To test this hypothesis, polystyrene 96-well plate surfaces were modified to possess similar topographies as those of B-lymphocyte cell membranes. This was accomplished by immobilizing Protein A conjugated gold particles and Protein A conjugated polystyrene particles ranging in sizes from 40 to 860 nm to the bottom of polystyrene wells. Atomic force microscopy results provided evidence of well-dispersed immunoassay-biosensor surfaces for all particles tested with high degrees of biologically inspired nanometer roughness. Testing the functionality of these immunosurfaces using antigenic fluorescent microspheres showed that specific antigen capture increased with greater nanometer surface roughness while nonspecific antigen capture did not correlate with surface roughness. In this manner, results from this study suggest that large degrees of biologically inspired nanometer surface roughness not only increases the amount of immobilized antibodies onto the immunosurface membrane, but it also enhances the functionality of those antibodies for optimal antigen capture, criteria critical for improving immunoassay-biosensor sensitivity and specificity.